Commit 760de791 authored Nov 30, 2015 by Jaegeuk Kim

f2fs: avoid deadlock in f2fs_shrink_extent_tree



While handling extent trees, we can enter into a reclaiming path anytime.
If it tries to release some extent nodes in the same extent tree,
write_lock(&et->lock) would be hanged.
In order to avoid the deadlock, we can just skip it.

Note that, if it is an unreferenced tree, we should get write_lock(&et->lock)
successfully and release all of therein nodes.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

parent 57b62d29

fs/f2fs/extent_cache.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -615,9 +615,10 @@ unsigned int f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
		for (i = 0; i < found; i++) {
		struct extent_tree *et = treevec[i];

		write_lock(&et->lock);
		if (write_trylock(&et->lock)) {
		node_cnt += __free_extent_tree(sbi, et, false);
		write_unlock(&et->lock);
		}

		if (node_cnt + tree_cnt >= nr_shrink)
		goto unlock_out;